Ventilator wheel or fan wheel with antibacterial coating

ABSTRACT

The present invention relates to a ventilator wheel or fan wheel composed of a hub and blades which are fastened in said hub. The hub and/or the blades are at least partially provided, on the surface thereof, with an antibacterial agent.

The present invention relates to ventilator wheel or fan wheelconsisting of a hub and blades fastened thereto, and to a ventilator ora fan using such a ventilator wheel or fan wheel.

Filter material and cable surfaces of air conditioning equipment andcooling or ventilation equipment become contaminated over time by layersof grime and grease settling on them. These layers contain bacteria andfungi which can be spread further via the stream of air. This may leadto allergies and infections in people who spend time in the particularair-conditioned or ventilated room.

In order to avoid this or to reduce this risk, it is known to providethe respective surfaces of the air-conveying parts of the equipment withan antibacterial or antimicrobial coating. Suitable active ingredientsfor this purpose are nanoscale molecules of metal complexes of preciousmetal such as e.g. silver, copper, molybdenum or the like. It is alsoknown to use for this purpose ceramic carriers in powder form providedwith silver ions, as a result of which metal ions are reversibly bondedto the metal surface.

It was found that purely metallic colloidal metal particles, likeso-called “nanosilver particles”, only have a highly restricted, inparticular not long-lasting efficiency, while metal ions have a strongerand more sustained effect. For various reasons, such as the toxicity orcorrosive effect of some substances with ionic bonding, these substancescannot always be used, however.

With regard to silver oxide, for example, it should be noted that it isnot optimally suitable for the indicated application because whenexposed to air it transforms into silver carbonate, which can in turnhave skin irritating effects, so that protective gloves have to be wornwhen handling this substance. Also known is the strong irritating effectof silver nitrate, which is, for example, used because of its causticeffect in the medical field as “Höllensteinstift™”, for removing warts,is likewise known.

Compared to other appliances, like, for example, medical devices,refrigerators, refrigerated counters, dashboards in vehicles, mousepads, etc., the difference in fan wheels or blower wheels is that, inthe operating state, the antibacterial substances are not normally incontact with the human body, like hands, or with food, but only with theair streaming through the fan or blower which requires increasedoligodynamic efficiency to guarantee antibacterial or antimicrobialprotection. There is such direct physical contact, however, duringproduction and assembly, so that physiologically questionable substancescannot be used.

The object of the present invention is to make the transmission route ofbacteria, fungi, viruses, i.e. germs in ventilation technology evensafer against the transmission of these germs.

According to the invention, this is achieved by, for ventilator wheelsor fan wheels present in ventilation equipment, providing the hub and/orthe blades on their surface at least partially with an antibacteriallyeffective active ingredient.

Furthermore, according to the invention, it is advantageous if theventilators or fans which are used, which consist of a housing,preferably with a safety grid, and a ventilator wheel or fan wheelstored in the housing, and of an electric motor driving this, and of amotor mounting, have an antibacterially effective active ingredient onthe surface at least of their air-conveying housing sections.

As substances with antibacterial effects, mainly nanoscale aggregatedmolecules of metal complexes, in particular of noble metals like silver,copper, molybdenum or the like, can be used. These molecules havebiocidal, oligodynamic and antimicrobial effects. By using coatingscontaining nanoscale molecules of this type, the correspondingly coatedsurface is prevented from being infested by bacterial and viralmicroorganisms like fungi. The nanoscale molecules prevent the formationof a biofilm and cause the destruction of microorganisms on the coatedsurface.

According to the present invention, in a preferred embodiment monovalentand preferably divalent silver or copper, which respectively forms thecentral atom of the complex, can in particular be used as metalcomplexes. They can be formed with hydroxycarboxylic acids like, forexample, 2-hydroxypropanoic acid (lactic acid),2-hydroxypropane-1,2,3-tricarboxylic acid (citric acid) or2,3-dihydroxybutanedioic acid (tartaric acid), as substances formingligands in the complex ions.

Also ammine complexes of the chemical formula [Ag(RNH₂)₂]⁺, where R ishydrogen, a methyl or an ethyl group, for example, can preferably beused. These complexes are characterized, in particular, by increasedstability in comparison to other complexes.

It is particularly advantageous to use mixed copper- andsilver-containing compounds because it has been found that, wheninteracting, copper and silver ions have a synergy with regard to theoligodynamic efficiency, which can be explained by the occurrence ofdifferent and reciprocally interacting mechanisms of action. Inparticular, catalytic oxidation, which inhibits the supply of oxygenrequired for the survival of the microorganisms, a reaction with thecell membranes and their proteins, which inhibits the ingestion, and abinding to enzymes and nucleic acids of the microorganisms, whichprevents their reproduction, are considered to be such mechanisms ofaction. Each mechanism of action can be selectively influenced todifferent degrees by the copper and silver, which, in the interaction ofthe different ions, results in that the oligodynamic efficacyprogressively increases with concentration, but is disproportionatelyhigher compared to the same concentrations in which only silver or onlycopper is present.

Copper (I) and silver (I) diammine complexes and/or copper (II) andsilver (II) tetra-ammine complexes, or also possibly mixed aqua-amminecomplexes can thus, for example, be used advantageously not onlyrespectively alone, but also preferably as a mixture. A higher efficacyshould be attributed to the ions of divalent metals because of theirhigher redox potential.

The respective ligands of the substances constituting the complex ionsneed not necessarily be organic compounds, as described above. Thecomplex can, for example, also be inorganic compounds, like athiosulfato compound, which, for example, contains thebis(thiosulfato)argentate ion [Ag(S₂O₃)₂]³⁻.

As is also apparent from both preceding exemplary chemical formulas, thecomplex ions can be cations as well as anions. The respectivelycomplementary anions or cations in the complex compounds can be thoseresulting in salts that are easily soluble, hardly soluble or insolublein water, the formation of soluble substances being favorably associatedwith the advantage of higher ion mobility, and the formation ofinsoluble or hardly soluble salts with the advantage of an easierextraction of nanoparticles by means of colloidal precipitation.

While the chemical binding of the corresponding metals in the complexions can attack the microorganisms with a marginally reduced intensityas compared to the free metal ions in short-term usage, but apotentially harmful effect on the human body is advantageouslyeliminated, on the one hand, and on the other, a prolonged effect isensured compared to free metal ions.

It has surprisingly been found that silver-containing sulfonamides, likesilver sulfadiazine (empirical formula: C₁₀H₉AgN₄O₂S) in particular,which, as is known, is used as an antibacterial active ingredient fortreating second and third grade burns as well as extensive lacerations,has an oligodynamic effect on the surface of hubs and/or blades of fansand/or blower wheels which are in contact with the air streaming throughthem. This results in a synergistic effect of the acid residue of theamide-containing sulfonic acid and silver ions.

Although high ion mobility is desirable in line with the presentinvention, it is evident that from the possibility of using silversulfadiazine that the antibacterial active ingredient, such as silverchromate Ag₂CrO₄, need not necessarily be water soluble, but may also bewater insoluble, such as silver dichromate AgCr₂O₇.

The active ingredient can also be a ceramic carrier with e.g. silver oroligodynamic ions bound therein, aluminum silicate being particularlyused as a ceramic carrier. By means of an active ingredient of thiskind, in which the active ingredients are preferably kept in a zeoliticcage matrix, and which can be introduced into the coating in powderform, it is possible to sustain a long term dosed release of the activeingredient.

The presence of hydroxyl groups in the active ingredient, like thosecontained in the above mentioned hydroxycarboxylic acids, has aparticularly advantageous effect because by interacting with them themetals on the surface of the hub and/or blade can have a higher, stillphysiologically harmless, concentration than is permissible for freecopper or silver ions, for example. The hydroxyl groups can be bound indifferent ways, preferably chemically, in the ceramic matrix.

According to the invention, the antibacterially effective activeingredients can be incorporated into paints, powder coatings or plasticsmixtures, meaning that they can be applied either as a coating to thesurface or in the form of a paint coat or a surface film by adding themto these particular materials in a different concentration depending onthe requirements. In particular, alkyd, acrylic, epoxy or polyurethaneresins are possible options as basic formulations for the lacquers.Polyolefins, in particular polyethylene and polypropylene as well aspolyvinyl chloride, are suitable as base materials for the surfacefilms. It is likewise possible to mix the antibacterially effectiveactive ingredients into the manufacturing material of the ventilatorwheel or fan wheel or parts of the ventilator housing or fan housing.

Ventilators or fans usually consist of a housing in which the ventilatorwheel or fan wheel is rotatably stored, where the ventilator wheel withthe electric motor integrated therein is fastened to a motor mounting.Moreover, the housing can be provided with a safety grid. It is withinthe scope of the invention if the parts of the ventilator, in particularthose which are air-conveying and/or are located in the stream of air tobe conveyed, are provided on their surface in an antibacterial mannerwith an active ingredient according to the invention. Here, theconcentration of the active ingredient coating on the individual partscan be the same or different depending on where the highest bacterialloading is expected. It has been found that the total concentration ofthe oligodynamic metals, preferably present in ionic form, on thesurface of the hub and/or blades should optimally be in the range of0.05 to 15% by mass, preferably in the range of 0.2 to 2.8% by mass.

The design of the particular ventilator is not essential to theimplementation of the invention, meaning that it can be used for anytype of ventilator; in particular, axial and radial ventilators arecustomary.

The present invention is not restricted to the illustrated and describedexemplary embodiments, but also comprises all identically functioningmeans within the meaning of the invention. Apart from silver, copper andmolybdenum, which are mentioned above as biocidal metals, cadmium and/orvanadium can, for example, also be used within the scope of the presentinvention. Mixtures of the above substances, mentioned above as singlecompounds or compound groups, can also be used.

Furthermore, the present invention is not restricted to the combinationof characteristics defined in claims 1 and 23, but can also be definedby any other combination of certain characteristics of all disclosedindividual characteristics. This means that basically each individualcharacteristic of the independent claims can be omitted and/or replacedby at least one individual characteristic disclosed at another point ofthe application. To that extent, the claims are to be merely understoodas a first attempt at formulating the invention.

In connection with the use of photosensitive silver compounds, likesilver chromate, it should be noted that it is also within the realm ofthe present invention that the efficacy of the antibacterial activeingredient on the surface of the hub and/or blades only graduallydevelops or increases as a result of environmental effects, and also asa result of the action of light, acids, etc.

For the purpose of the present invention, nanoscale particles areunderstood to be particles from monomolecular size up to an averageparticle diameter of 1000 nm. The average particle diameter shouldpreferably be in the range of 1 nm to 40 nm, especially preferably inthe range of 15 nm to 30 nm. With a disproportional increase of thespecific particle surface when the particle size decreases, theoligodynamic efficacy also increases accordingly because a largerreaction surface is available for chemical and physical reactions likethe already mentioned catalytic reaction or, among others, for theadsorption and absorption reactions, and in addition, the smallerparticles also have a higher mobility.

Antibacterial within the context of the invention means both effectiveagainst bacteria and also against viruses and fungi.

1. A ventilator wheel or fan wheel comprising a hub and blades fastenedtherein, wherein at least one of the hub and the blades are provided ontheir surface at least partially with an antibacterially effectiveactive ingredient.
 2. The ventilator wheel or fan wheel as claimed inclaim 1, wherein the active ingredient contains nanoscale aggregatedmolecules of oligodynamically active metal complexes.
 3. The ventilatorwheel or fan wheel as claimed in claim 2, wherein metals of theoligodynamically active metal complexes are selected from the groupconsisting of silver, copper, molybdenum and vanadium.
 4. The ventilatorwheel or fan wheel as claimed in claim 2, wherein monovalent or divalentsilver or copper is present in the oligodynamically active metalcomplexes as a central atom as well as ligands of at least onehydroxycarboxylic acid.
 5. The ventilator wheel or fan wheel as claimedin claim 4, wherein the hydroxycarboxylic acid is selected from thegroup consisting of 2-hydroxypropanoic acid (lactic acid),2-hydroxypropane-1,2,3-tricarboxylic acid (citric acid) or2,3-dihydroxybutanedioic acid (tartaric acid).
 6. The ventilator wheelor fan wheel as claimed in claim 2, wherein monovalent or divalentsilver or copper is present in the oligodynamically active metalcomplexes as a central atom as well as one or both of ammine ligands andaqua-ammine ligands.
 7. The ventilator wheel or fan wheel as claimed inclaim 6, wherein the oligodynamically active metal complexes with theammine ligands have the empirical formula [Ag(RNH₂)₂]⁺, R being hydrogenor a methyl or ethyl group.
 8. The ventilator wheel or fan wheel asclaimed in claim 1, wherein the active ingredient contains silver aswell as copper, each of which is present in ionic or bound form in ametal complex.
 9. The ventilator wheel or fan wheel as claimed in claim4, wherein a bis(thiosulfato)argentate is formed as a ligand bymonovalent or divalent silver.
 10. The ventilator wheel or fan wheel asclaimed in any claim 1, wherein the active ingredient contains silversulfadiazine.
 11. The ventilator wheel or fan wheel as claimed in claim1, wherein the active ingredient contains a hydroxyl group-containingcompound.
 12. The ventilator wheel or fan wheel as claimed in claim 1,wherein the active ingredient is insoluble in water.
 13. The ventilatorwheel or fan wheel as claimed in claim 2, wherein the active ingredientincludes a ceramic carrier, the ceramic carrier being aluminum silicatewith silver, copper or other oligodynamically effective metal-containingions bound therein.
 14. The ventilator wheel or fan wheel as claimed inclaim 1, wherein the active ingredient contains particles having a sizein the range from a monomolecular dimension up to an average particlediameter of 1000 nm.
 15. The ventilator wheel or fan wheel as claimed inclaim 14, wherein an average particle diameter of the active ingredientis in the range of 1 nm to 40 nm.
 16. The ventilator wheel or fan wheelas claimed in claim 2, wherein an average particle diameter of theactive ingredient is in the range of 15 nm to 30 nm.
 17. The ventilatorwheel or fan wheel as claimed in claim 2, wherein the oligodynamicallyactive metal complexes on the surface of the hub and/or blades have ametal concentration that is in the range of 0.05 to 15% by mass.
 18. Theventilator wheel or fan wheel as claimed in claim 17, wherein the metalconcentration of the oligodynamically active metal complexes on thesurface of the hub and/or blades have a metal concentration that is inthe range of 0.2 to 15% by mass.
 19. The ventilator wheel or fan wheelas claimed in claim 1, wherein efficacy of the active ingredientgradually increases as a result of environmental effects, including as aresult of the action of light or acids on the surface of the hub orblades.
 20. The ventilator wheel or fan wheel as claimed in claim 19,wherein the active ingredient is contained in a surface coating on atleast one of the hub and blade.
 21. The ventilator wheel or fan wheel asclaimed in claim 20, wherein the surface coating of the hub or blade isone a spray coat, a paint coat or a film.
 22. The ventilator wheel orfan wheel as claimed in claim 1, wherein the active ingredient is mixedinto a manufacturing material of the ventilator wheel or fan wheel. 23.A ventilator wheel or fan wheel as claimed in claim 1, incorporatedwithin a housing, having a safety grid, motor mounting and an electricmotor driving the ventilator wheel or fan wheel.
 24. The ventilatorwheel or fan wheel as claimed in claim 23, wherein the housing has anantibacterial active ingredient on its surface.
 25. The ventilator wheelor fan wheel as claimed in claim 24, where on their surface at least oneof the motor mounting safety grid of the housing have an antibacterialactive ingredient on at least air conveying sections thereof.
 26. Theventilator wheel or fan wheel as claimed in claim 25, wherein the activeingredient contains nanoscale aggregated molecules of oligodynamicallyactive metal complexes.
 27. The ventilator wheel or fan wheel as claimedin claim 26, wherein the antibacterial active ingredient is contained ina surface coating being one of a paint coat, a spray coat or a film. 28.The ventilator wheel or fan wheel as claimed in claim 26, wherein theantibacterial active ingredient is mixed into a manufacturing materialof the ventilator wheel or fan wheel.